1. Field of the Invention
The present invention relates to a computer pointing device, and more particularly, to a computer pointing device which uses capacitors installed in various directions to generate pointing signals.
2. Description of the Prior Art
Pointing devices are commonly used for controlling movements of a cursor or an object on a computer screen. Several types of pointing devices such as mouse, track ball, digitizer, joystick, point stick, etc., are currently sold in the market. Compared with other pointing devices, the point stick is very small and can be easily installed on a keyboard. A point stick usually comprises an upward protruding handle and a plurality of pressure sensitive resistors corresponding to various directions disposed under the handle for sensing a tilted direction of the handle. When the handle is tilted toward one direction, the resistance of these resistors will be changed accordingly. And the resistance of all the resistors will be detected and converted into pointing signals to reflect the tilted direction and exerted pressure of the handle. The pointing signals will be used to control movements of a cursor shown on a monitor screen.
The drawback of the above mentioned point stick is that it uses the pressure sensitive resistors to sense the tilted direction and exerted pressure of the handle. The moving speed of the cursor is made proportional to the pressure exerted on the handle. Such design makes it quite difficult to accurately control the moving speed of a cursor by using a finger because the finger force exerted on the handle can not be accurately controlled by a user. Besides, the pressure sensitive resistor may be damaged after a long period of use which will affect its capability in accurately sensing the force exerted on the handle.